Polymers of carbon monoxide and olefinically unsaturated organic compounds, or polyketones, have been known and available in limited quantities for many years. For example, polymers of ethylene or ethylene-propylene which contain small quantities of carbon monoxide are disclosed in U.S. Pat. No. 2,495,286, prepared using free radical catalysts. British Patent 1,081,304 discloses polymers containing higher concentrations of carbon monoxide prepared using alkylphosphine complexes of palladium salts as catalysts. A special class of linear polyketones is disclosed in U.S. Pat. No. 3,694,412, wherein the monomer units of carbon monoxide and olefinically unsaturated hydrocarbons occur in alternating order.
Polyketones are of considerable interest because they exhibit good physical properties. In particular, the high molecular weight linear alternating polymers have potential use as engineering thermoplastics due to their high strength, rigidity and impact resistance. These polymers consist of repeating units of general formula ##STR1## which units may be the same or different and wherein A is the moiety obtained by polymerisation of the olefinically unsaturated organic compound through the olefinic unsaturation.
Although the properties of the polyketones are suitable for many applications, it would be of advantage to provide polyketone composites which exhibit less mould shrinkage and certain mechanical properties that are improved over the corresponding properties of the polymer alone.
EP-A-322959 describes a reinforced thermoplastic composite comprising a linear alternating polymer of at least one olefinically unsaturated compound and carbon monoxide, and a glass fiber reinforcement. Herein it is mentioned too that glass fibers that are to be used as a reinforcement in plastics, customarily have a coating of a sizing material. The chemical structure and the manner of deposition of such a sizing material on the glass fibers often is a manufacturer's secret; and most end users have grown accustomed to referring to the code name of the fiber manufacturer rather than to a chemical formula. Nevertheless a number of different chemical compounds are mentioned as suitable sizings in EP-A-322959, e.g. water emulsions of starch and lubricating oil, aqueous dispersions of surface active materials and lubricants, silicon-containing materials such as vinyl silanes, alkyltrimethoxysilanes, aminosilanes, trimethoxysilanes which may also contain urethane, acrylate or epoxy functionalities, and non-polar hydrocarbons. For use in glass fiber based composites, a preference is expressed for polar sizings having a trimethoxysilane end group attached to a hydrocarbon chain with a terminal urethane functionality, for instance the sizing used in the fibers sold by Owens Corning under the code name 492 AA.
Whereas the mechanical properties of such composites are quite satisfactory, they could still be improved. Another problem, up to now not recognised, is that certain sizings, by their very reactivity with the polymer molecules, cause cross-linking between different polymer molecules. This phenomenon does not occur in polymers like polyethylene or polypropylene, which lack any reactive (carbonyl) groups. If the suitability of a certain fiber-sizing combination for use in polyketone based composites is judged solely on the basis of impact strength and similar mechanical tests, as is customary for conventional polymers, the cross-linked polymer composites will appear very attractive, because of their high scores in such tests. However, as soon as such glass fiber reinforced composites have to be processed, e.g. extruded, from the melt, it is found that their melt viscosity is so high that they are practically improcessable. This phenomenon of cross-linking was found to occur inter alia with the polar sizing recommended in EP-A-322959, and has now been found to occur with many other sizing.
It was recently found by the Applicant that a method to improve the performance of such polyketone composites is to incorporate reinforcing materials into the polyketone polymer matrix and especially inorganic fibrous reinforcements.